Method of manufacturing heat exchange devices



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METHOD OF MANUFACTURING HEAT EXCHANGE DEVICES Original Filed June 17,1959 `\`\SS.\`S

April 28, 1942.

Patented Apr. 28, 1942 2,281,207 y ICE.

METHOD F MANUFACTURING HEAT EXCHANGE DEVICES Paul F. Schoen, Dearborn,Mich., assignor to Bohn Aluminum & Brass Corporation, Mich., acorporation of Michigan Detroit,

Original application June 17, 1939, Serial No.

Divided and this application February 1, 1940, Serial N0. 316,803

1 Claim.

This invention relates to a method of manufacturing heat exchangedevices.

A primary object of the invention is to provide a structure of improvedeconomy and efficiency, and this object is accomplished by constructionof the heat exchanger from tubing extruded from aluminum or othersuitable material. 'I'he vci tubing is extruded with iins on both theinnerl and outer diameters, and the tubing is twisted to give the fins aspiral form, which increases the heat-exchange eiciency and improves thephysical properties of the tubing. If the tubing is to be bent informing a heat-exchange unit, the part to be bent is kept in morepliable condition by not twisting it, and the external ns are removedprior to bending.

These and other objects and advantages of the invention will becomeapparent as the description proceeds.

While preferred forms of the invention are disclosed herein for purposesof illustration, Various changes may be made in the method withoutdeparting from the spirit of the invention as herein set forth andclaimed.

This application is a division of my application Serial No. 279,690,filed June 17, 1939, which claims the article resulting from the method.

In the drawing:

Fig. 1 is a plan view of a heat exchange device l embodying theinvention.

Fig. 2 is a section on line 2--2 of Fig. 1.

The invention is illustrated in connectionY with a unit for applicationto a wall or ceiling of a cold storage room, although obviously thenovel features may be used in heat exchange devices for other purposes.

The cooling unit illustrated consists of a single length of tubing I0,which is extruded with a plurality of externall ns II and with aplurality of internal ns I2. This tubing is preferably extruded fromcommercially pure aluminum, although other suitable materials may beused.

At places where the tubing is to be bent, such as at I3, the outer finsare sheared off to prevent any interference with the bending operation.

As the result of the extruding operation, the flns II and I2 areoriginally alined with the longitudinal axis of the tubing. In order togive the ns of the tubing a spiral shape the length of the tubing to bespiraled, for example the straight run I4, is twisted while undertension. This is preferably done by applying clamps to the outside ofthe tube at the points I5 and I6, and rotating one of the clamps whilepulling it away from the other clamp. This operation maintains the tubepreferably straight and gives an even and uniform spiral shape to theiins, the pitch of the spiral depending on the number of turns given tothe movable clamp.

The run I4 is preferably twisted while the entire piece I0 is a straightlength, and it is to be understood that'this first twisting operationdoes not twist the tube beyond the point I6, -so that the internal iinsat the place I3 have not been spiraled.

'I'he next operation is to bend the tube at the place I3. Inorder toprevent collapse of the tube and of the internal ns a mouse formed of aplurality of exible elements, such as Wires. is drawn into the tubing tothe place I3, and the tube is then bent in the desired direction.

The next run I5' of the tubing is then spiraled, and the bend I1 is nextformed, these operations being repeated until the unit illustrated isformed. As an alternative method the different runs of the tubing can bespiraled While the tubing I0 is in one straight piece if suitablearrangements are made to keep the sections where the bends are to bemade in their original un twisted condition. l

The external flns areremoved at the ends I8 and I9 in order to provide asmooth tubeadapted for connection with the tubing of a refrigerationsystem. The internal fins may also beremoved at the ends I8 and I9 ifdesired.

Among the advantages of the above construction are the fact that thetwisting of the tube to spiral the iins elongates the edges of the ns,which were extruded as thin as possible, thus thinning them andincreasing their eflciency for heat conduction. At the same time thetubing itself is shortened and thickened, thus increasing the safetyfactor on the tube. 'I'he spiral fins serve as very stili ribbingagainst bending of the tube sections, and the bending of the ns inspiraling serves to cold-work the fins, increasing their hardnessagainst external damage.

'I'he spiral tins make very eflicient contact with air currents, sinceair moving across the ltube is directed around the spiral iins, makingwiping contact with the tube and the ns. The spiral shape of the nsavoids any pockets in which condensation might collect.

The runs I4, I 5, etc., need not be parts of a single tube, but can beseparate pieces connected together or to a header by suitable fittings.

I claim:

The method of producing a heat exchange device which comprises extrudinga length of tubing having internal and external longitudinal fins,giving the nson certain parts of the tub'- ing a spiral form relative tothe tubing, removing the external fins from the ends of the tubing andfrom certain parts intermediate the ends,l

and bending the tubing at said intermediate i,

parts.

' PAUL F. SCHOEN.

